Oxidized wax and process for producing same



Patented June 7, 1938 PATENT OFFICE OXIDIZED WAX AND PROCESS FOR PRO-DUCING SAME Donald E. can. Long Beach. and Maner L. Wade,

Naples, Calit, alsis'l ors to Union Oil Companyofcaiii'orniallosm mcalifacorporationof California Drawing. Application July o, 1936,

' Serial No. 89,132

Claims. (01; 190-21) I The present invention relates to the art ofseparating wax from wax-bearing oil, and more particularly the inventionpertains to a method in which certain materials are added to thewaxbearing oil to condition the latter so that the wax may be morereadily separated from the oil. The invention also relates to a processfor the production of materials which when added to a wax bearing oil,condition the latter so that the wax may be more readily removedtherefrom. The invention is also applicable for the separation of oilfrom wax such as slack wax, wax cakes. etc. This application is acontinuation in part of our copending application Serial No. 37,940filed August 26th, 1935.

Many oils contain relatively large quantities of wax which impart a highpour point to the oil and thereby render these oils unsuitable for useas they are solid and will not flow at ordinary temperatures. In orderto render these oils fluid at ordinary temperatures, it is necessary toremove the wax present. This is usually accomplished by adding asuitable diluent to the waxbearing oil, chilling the diluted oil to atemperature suillcientiy low to precipitate or solidify the wax and thenseparatim the precipitated wax from the diluted oil by settling,filtering or centrii'uging.

We have discovered that wax present in oils may be more readilyseparated by mixing the wax-bearing oil with certain materials whichrender the wax more readily separable from the oil. Hereinafter, thematerials which we employ to condition the wax present in wax-bearingoils in order that the wax may be more readily separated from the oilwill be referred to as "wax modifiers" or wax separation aids;

In general, the wax separation aids which we employ to condition thewax-bearing oil to render the wax more readily separable, compriseoxidized parailinic substances. Such oxidized parafllnicsubstancesinciude oxidized waxes, such as scale wax, slack wax,chemically refined water white high or low melting point waxes, oxidizedpetrolatum, oxidized ceresin, oxidized oils containtaining large orsmall quantities of wax and/or petrolatum, oxidized raflinates producedby solvent extraction of oils and which may be substantially free fromwax or may .contain large or small quantities of wax, oxidized petroleumdistiilates either substantially free from wax or containing large orsmall quantities of wax and oxidized petroleum residues eithersubstantially free from wax or containing large or small quantitles ofwax. We have discovered that the foregoing oxidized wax separation aidsare quite active in conditioning the oil to be dewaxed so that the waxmay be more readily separated from the oil. The reason for thisphenomenon is not definitely known but we do know that when smallamounts of the oxidized material are added to the oil to be dewaxed, animprovement is obtained with respect to the yield of dewaxed ,oil,filter rate or rate of wax separation and melting point of the separatedwax. When the same amount of the materials prior to their oxidation areadded to wax-containing oils, the improvement obtained is not sumcientlyincreased with respect to yield, filter rate and quality of the waxseparated over the unaided dewaxing process as to warrant their use incommercial dewaxing processes.

In general, the oxidized wax separation aids may be produced bysubjecting the unoxidized waxes or oils to the action of anoxygen-containing. gas such as air, oxygen or ozone, preferably at anelevated temperature. Certain types of materials among those mentionedabove require no treatment, chemical or otherwise, previous to oxidationto produce the active wax separation aid. However, it is beneficial inthe case of certain stocks, such as crude slack waxes, to prepare themfor more effective oxidation by a preliminary removal of undesirableimpurities, such as resins, reactive oil fractions, etc.

Preferably, when producing the wax separation aid from slack waxes orwaxes containing considerable quantities of oil, the crude wax is firstdeoiled to a low oil content. This may be accomplished by dissolving thewax in a suitable solvent, then chilling the solution to reprecipitatethe wax and filtering the mixture. As deoiling solvents. we may employany of the solvents mentioned hereinafter for diluting the wax bearingoil in the dewaxing thereof. We prefer, however, to employ theliquefled'normally gaseous hydrocarbons such as ethane, ethylene,propane, propylene, butane, butylene or mixtures thereof. butane. It ispreferable to effect the deoiling of the wax at a higher temperaturethan the temperature at which the slack wax was separated from the oilwhich in propane dewaxing is approximately 40 F. Thus, we may dissolvethe slack wax separated from lubricating oil at a temperature of about40 F. in propane or butane at a temperature suillcient to dissolve thewax, for example F. to F., chill the solution to about 25 F. andseparate the liquid constituents from the crystallized wax by filtra- 56Of these, we prefer to use propane or good results in deoiling slackwaxes by the use of a mixture of solvents such as liquefied normallygaseous hydrocarbons, such as propane and an aromatic solvent such asbenzene or toluene.

The crude deoiled wax may be subsequently acid treated. This is for thepurpose of removing asphalt and other easi y oxidized materials whichseem to be reactive with oxygen or other oxygen-containing gas inpreference to the parafiinic components. In other words, we have foundthat when wax is contaminated with large quantities of low A. P. I.gravity materials, these latter materials prevent the proper course ofoxidation to such an extent that it is not feasible to produce adewaxing aid from such stocks. The acid treatment also reduces the ratioof oil to wax in the slack wax and leaves only the more stable oils inthe slack wax. when the wax has been suiiiciently deoiled, the acidtreatment may not be necessary providing no considerable proportions ofasphalt or resinous materials are present in the wax. If desired, thecrude slack wax may be deoiled and deresinated by spraying the wax at atemperature above its melting point into a bath of liquid propanemaintained at 40 F. This causes the wax to solidify in discreteparticles and sufficient time is allowed for the propane to leach theoil from the solidified particles. The recovered wax may then be heatedto above its melting point and allowed to stand. By decanting the waxwhile fluid, it will be found that the asphalt and resinous materialshave settled to the bottom of the vessel.

The acid treatment will; of course, vary with the type of crude waxtreated but will usually be at about 10 to 25 F. above the melting pointof the wax. The acid treatment should be carried out in stages employingthe proper amount of acid, such as 98% sulfuric acid, consistent withgood settling of sludge produced by the reaction with the acid. Thesludge produced by the first dump of acid may be quite viscous,especially if not withdrawn promptly. Therefore, care should be taken toobtain suflicent agitation and settling without permitting the sludge tohave time to thicken excessively. After the last of the sludge isseparated from the wax, the latter is heated to a temperature between140 to 200 F. which is sufiicient to reduce the viscosity of the wax foralkali treatment and water washing. The water washing between the acidand alkali treatments may be started immediately after withdrawing thesludge and may be continued as the temperature is raised. The waterwashing need not be extremely thorough to remove soaps and excesscaustic after neutralization. In fact, the presence of a small amount ofthe sodium I compounds have been found to be beneficial in thesubsequent oxidation step. As a matter of fact in one run for theproduction of oxidized wax, none of the sodium hydroxide used forneutralizing the wax was separated and the dehydrated charg therefore,contained an unusual excess of the caustic which was reflected in a verylow acid number (0.1) in the blown product. Nevertheless, this batch ofoxidized wax showed a very high filter aid quality. 1

The wax, either chemically treated and/or deoiled as the case may be, isthen subjected to oxidation. The conditions and degree of oxidation willvary with the type and oil content of the wax. In general. the morecompletely deoiled and refined waxes will tolerate a higher degree ofoxidation than waxes which contain substantial quantities of oil. Theoxidation consists in heating the wax to a temperature of between 350and 500 F. and introducing air, oxygen or ozone into the charge until asufficient oxidation has taken place to render the material active as awax separation aid and yet retain its compatibility with the oil to bedewaxed. During the oxidation, there is a period of, induction duringwhich little or nothing appears to be happening.

This may last up to twelve hours or longer, de-' move fairly rapidly,and it is desirable to stop the oxidation before the charge reaches astage where it is only sparingly compatible with the waxy oil to bedewaxed.

The degree of oxidation may be determined approximately by measuring theacid and saponiflcation numbers of the oxidized charge. However, thesevalues are not entirely indicative of the wax separation aideffectiveness of the charge since the optimum amount may vary withdifierent types of charging stocks. For example, with an acid treatedslack wax, whereas the oxidation should not be carried to an acid numberabove 5 and a saponification number above 30,

in the case of substantially deoiled and refined waxes, the oxidationmay be continued until the charge has an acid number between 15 and 100and a saponification number between 80 and 300. The acid andsaponiflcation numbers are determined according to the methods outlinedby the American Society of Testing Materials,methods D-188-27T andD-94-28, respectively.

Also, indicative of the degree of oxidation of the charge, are theincreases in specific gravity, viscosity and melting point. In general,the oxidation should not be carried to such a point that the viscosityand melting point are excessively high, rendering the subsequenthandling of the oxidized material difllcult. Also, we have found thattoo much blowing or oxidation of the wax charge results in theproduction of a product which causes plugging of the filter cloth in thedewaxing operations.

We have also found that the substances to be oxidized may be efficientlyoxidized to produce wax separation aids by the use of hydrogen peroxide.The oxidation with hydrogen peroxide may be carried out advantageouslyin the presence of a stream of air or oxygen while maintaining thecharge at an elevated temperature. The hydrogen peroxide may be addedcontinuously to the charge as a liquid solution while maintaining thecharge at an elevated temperature. Preferably, air is simultaneouslyintroduced into the heated charge while adding the hydrogen peroxide. Ifdesired, air may be passed through a separate vessel containing hydrogenperoxide and the activated air or oxygen thence passed into the heatedcharge. The temperature to which the charge is heated will depend uponthe nature of the particular charge to be oxidized. Paramns, forexample, may be satisfactorily oxidised at-a temperature between 850 to400 1''. The use of paraillns oxidized with hydrogen peroxide isadvantageous with respect to the color of the oxidized wax obtained.Hydrogen peroxide, in addition to being an eil'ective oxidising agentexerts abieaching action on the wax producing a very pale wax which doesnot impair the color of the dewaxed oil when employed as a waxseparation aid.

The oxidation reaction with air, oxygen or ozone or with hydrogenperoxide may be aided when the oxidation reaction is carried out in thepresence of catalysts. Catalysts which may be employed for this purposeare metal chlorides. such as the chlorides of iron, zinc, tin, aluminum,metal soaps such as the naphthenates (oieate's, stearates, ricinoleates.palmitates) of sodium, copper,- magnesium, aluminum mbalt and iron.

In carrying out our invention, a small amount, 1. e. 0.3 to 1% by volumeof the wax separation aid is mixed or dissolved in the wax-bearing oilafter which the mixture is chilled to a suiliciently low temperature toprecipitate or solidify the wax in the oil. The solidified wax may thenbe separated from the chilled mixture by settling, centrifuging orfiltering. The added wax separation aid will be precipitated and removedwith the wax. If desired, the wax separation aid may be first mixed ordissolved at an elevated temperature such as, for example, about 350 F.in a small quantity of the waxy distillates to be dewaxed. Theconcentrated solution may then be added to the waxy distillates in suchan amount so as to incorporate the desired amount of the wax separationaid.

Better results will be obtained when adding as wax separation aid suchoxidiaed waxes as are produced from the same types of oil as the oil tobe dewaxed. Thus, if it is desired to dewax an S. A. E. 20 waxy stock,it is preferable to employ an oxidised wax which was recovered from anS. A. E. 20 waxy stock; if it is desired to dewax an S. A. E. oil,superior results will be obtained by employing an oxidized 8. A. E. 50wax. Likewise,-when dewaxing S. A. E. 70 stocks, an oxidized 8. A. E. 70wax should be employed. The reason for this phenomenon is not definitelyunderstood, but we have found that by employing the oxidized wax fromthe same type oil to be'dewaxed, better results will be obtained withrespect to the yield of oil, filter rate and quality of the wax.

Itis preferable to employ as a-wax separation aid, the wax which isremoved from the same oil and which is oxidized. This means that the waxremoved from the oil will contain a small amount of oxidized wax whichwas added to the oil to be dewaxed. This mixture is then oxidized andemployed for aiding in the wax separation of further quantities of thesame oil. By this procedure, better results will be obtained due to thefact that the oxidized wax employed as a wax separation aid in dewaxingoils will produce a wax which will have a lower oil content and thus theseparated wax will oxidize into a wax separation aid having superior waxmodifying properties than one containing large amounts of oil.

Itwill be observed that when referring to an 8. A. E. 20, 50, 70, etc.waxy stock, we mean that the waxy distillate will yield upon completerefining, such as after separating the wax and low grade lubricating oilfraction such as those which are soluble in selective solvents such asliquid sulfur dioxide and the like, an oil corresponding to the range ofviscosities covered in the 8. A. I. designation is employed. By an S. A.E. 20, 50. 70, etc. wax, we mean a wax which. is separated from the waxydistillate having the particular 8. A. E. designation after dewaxing andselective solvent extraction.

In many cases, it is desirable to dilute the mixture of wax-bearing oiland'wax separation aid with a suitable diluent prior to the chillingstep in order to render the oil fluent at the dewaxing temperature. Asdiiuents for the wax-bearing oil, we may employ liquefied normallygaseous hydrocarbons such as ethane, ethylene. propane, propylene,butane, butylene or mixtures thereof, light hydrocarbons such aspentane, hexane, heptane octane, nonane, or hydrocarbon fractions suchas naphtha. gasoline, kerosene or gas oil. We may also employ suchdiiuents as acetone, mixtures of acetone and bensol, ethyl alcohol,propyl alcohol, butyl alcohol, methyl ethyl ketone.

diethyl ketone, methylpropyl ketone, ethylpropyl ketone, cyclohexanone,normally gaseous and normally liquid ethers, methyl chloride,dichlorethylene or trichlorethylene or mixtures of these materials withthe aforementioned hydrocarbons.

The use of a liquefied normally gaseous diluent such as liquid propaneis preferred since in addition to having the property of retaining lesswax in solution at low temperatures, it may be employed to produce thenecessary degree of refrigeration to precipitate the wax from thesolution by vaporizing a portion of the liquefied normally gaseousmaterial from the diluent oil under reduced pressure.

While the foregoing is specifically directed to the addition ofextraneous wax separation aids to oils to be dewaxed, we have alsodiscovered method of adding a small amount of the o'xidized waxseparation aid, since it involves the necessity of oxidizing the entirecharge of oil to be dewaxed, itis nevertheless within the scope of ourinvention.

It is thus an object of our invention to improve dewaxingcharacteristics of wax-containing oils by adding a small quantity of anoxidized wax to the oil to be dewaxed.

A further object of our invention resides in the use of oxidizedpetroleum fractions which were either substantially free from wax orcontain large or small quantities of wax prior to their .oxidation. suchmaterials being added in sufficient quantities of wax-containing oils toimprove their dewaxing characteristics.

Another object of our invention resides in a process for separating waxfrom oils by first oxidizin'g the wax-containing oil and then separatingthe wax from the oxidized oil.

-It is an important object of our invention to produce an oxidized waxfrom crude waxes by first subjecting the wax to precipitation and thenoxidizing the purified wax with air or other oxidialng gas.

It is a further object of our invention to accomplish oxidation bysubjecting the material to be employed as a wax separation aid for theoil to be dewaxed to the action of an oxygen-containing gas such as air,oxygen or ozone at an elevated temperature. It is also an object, of ourinvention to effect the oxidation by means of such liquids as hydrogenperoxide, preferably by agitating the material to be oxidized with air.It is a'further object of our invention to effect the oxidation in thepresence of catalysts. It is a further object of our invention toseparate as much of the oil contained in slack waxes as is possibleprior to oxidation to produce the wax separation aid.

A further object of our invention ruidcs in dissolving. the wax-bearingoil to be dewaxed and oxidized wax separation aid or the oxidized oil tobe dewaxed in a suitable diluent, chilling the mixture and separatingthe precipitated wax from the diluted oil. The use of a liquefiednormally gaseous hydrocarbon such as propane is preferred because thenecessary degree of refrigeration may be accomplished by vaporizing aportion of the diluent under reduced pressure.

It is a further object of .our invention to employ as a wax separationaid, an oxidized wax produced from oils of the same character as the oilto be dewaxed.

Many specific objects, features and advantages of our invention willbecome apparent to those skilled in the art as the description of ourinvention proceeds in connection with specific examples given belowwhich are not considered as limiting our invention but merelyillustrative of methods of carrying it out.

Examples of use of oxidized scale was:

A 6 gallon chargeof crude scale wax having a melting point of 123 F. washeated in a still to a temperature of 450 F. after which air was intro.-duced into the charge, first at a rate of 0.27 cu. ft. per minute forapproximately 72 hours and then at a rate of 0.40 cu. ft. per minute.The oxidized wax upon completion of the oxidation for 94 hours had anacid number of 7. a saponification number of 65, a melting point ofover- 300 F. and a specific gravity at F. of 0.865.

The oxidized crude scale wax was mixed in a closed vessel with an S. A.E. 20 waxy lubricating oil distillate obtained by the vacuumdistillation of a Santa Fe Springs crude oil. The oxidized crude scalewax was mixed with the waxy distillate at a temperature of about 300 1".and in an amount as to incorporate approximately 0.3% by volume into thewaxy distillate. The resulting mixture was then mixed with approximately4.5 volumes of liquid propane under superatmospheric pressure. Thetemperature .of the resulting mixture was about F. and the pressure wasthen chilled externally at a rate of approximately 3 F. per minute toaproximately -40 F., the refrigeration being accomplished by vaporizingunder gradually reduced pressure, a portion of propane in a jacketsurrounding the chilling vessel. The chilled slurry of propane,lubricating oil, solidified wax and wax modifier was filtered under apressure of about 25 lbs. per sq. in. to effect the separation of theprecipitated wax and wax modifier from the propane solution of thelubricating oil. The filter rate was 4.9 gallons per square foot offilter surface per hour based on the propane free oil. It will beobserved that all determinations of filter rates discussed herein arebased on the dewaxed 011 after separating the propane therefrom. Thefiltrate was thendistilled to remove the propane. Approximately 81.7% byvolume of dewaxed oil was recovered having a pour point of -5 F. Theseparated wax had a melting point of 130 1 as determined by the Galicianmethod.

In another run employing 1% of the above type wax modifier oxidized '12hours at 450 1''. on another portion of the same oil which was dewaxedunder the same conditions as above, except that a propane to oil ratioof 2 to 1 was employed, a filter rate of approximately 3.0 gaL/sq.ft./hr. was obtained. Approximately, 80.8% by volume of oil wasrecovered having a pour point of -10 1". The separated wax had a meltingpoint of 128 1".

The results obtained in the foregoing examples indicated that this typeof wax modifier is quite active in dewaxing oils when compared with ablank run wherein no wax modifier is emplged. The blank run on the sameoil and using same amount of propane and carried out under the samedewaxing conditions as above, showed that only 65.7% by volume of oilwas obtained having a pour point of -5 1''. The wax separated from theoil had a melting point of only 115 F.

A refined scale wax having a melting point of 123 I"., that is, a crudescale wax which was recovered from an S. A. E. 10 waxy distillate andwhich was deoiled and treated with sulfuric acid, neutralized withalkali and clay treated, was oxidined with pure oxygen at a temperatureof 450 F. for approximately 22 hours. The oxidized wax had an acidnumberof 10.4, and a saponification number of 106.3.

Propane dewaxing runs on an S. A. E. 20 waxy vacuum distillate accordingto the procedure described in the first example, employing 0.20, 0.50and 1.00% by weight of the oxidized wax modifier showed filter rates of8.3, 8.0 and 1.5 gal./sq. ft./hour, respectively, based on the viscousoil, yields of dewaxed oil of 81.9, 85.0 and 85.9% by volume,respectively, each having a pour point of -5 F. and separated waxes of128, 131 and 131 1''. melting point, respectively.

In another run, 1% by weight of the above oxidized refined scale wax wasemployed as a wax separation aid for dewaxing an S. A. E. 50 waxydistillate according to the propane dewaxing method described in thefirst example, employing, however, two volumes of propane to one of theoil.- A yield of 80.5% by volume of dewaxed oil was obtained having apour point of --5 1'. at afilter rate of 81.1 gal/sq. ft./hr. Themelting point of the wax separated was 1". according of the Ubbelohdemethod.

trample of use of oxidized S. A. E. 50 was:

A slack wax obtained by dewaxing an S. A. E. 50 waxy distillate whichwas produced by the vacuum distillation of a Santa Fe Springs crude oilwas first deoiled by dissolving it in propane and chilling the solutionto reprecipltate the wax and recovering the precipitated wax byfiltration. The deoiled wax was subsequently given a heavy acidtreatment and then wet neutralized preparatory to oxidation with pureoxygen. The acid treatment was carried out with 20 lbs. per barrel of103% sulfuric acid at a temperature of 210 1''. It was neutralized with35% of 5% caustic soda solution at 210 F. and water washed with threedumps of 100 volume percent each of water. The treated wax had a meltingpoint (Galician) of F. This material was then oxidized at a temperatureof 450? F. with pure oxygen for approximately 10 hours. The finishedproduct had an acid number of 16.0 and a saponification number of 82.2.

auaaeo whenanB.A.E.20vac\mmdistillatewasdewaxedinthepresenoeot 1%ofthismaterialacoording to the propane dewaxing method outlined in thefirst example, a yield of 83.0% by volume at -10 1". pour point oil wasobtained and a wax was recovered having a melting point (Galieian) of180 1''. The filter rate was approximately 6.6 gal-Ill. i't./hr.

Itissignifioanttonotethatwhentheunoxidised wax wasemployed as a dewaxingaid in dewaxing of the same character 011, according to the sameprocedure, the yield of oil obtained was only 69.2% by volume. This doesnot represent sufilcient improvement over the blank run described in thefirst example to indicate appreciable modifier action on the part of theunoxidised B. A. E. 50 wax. In another run, crude slack was was obtainedfrom a Santa Fe Billings S. A. E. 50 waxy distillate having a meltingpoint of 131 F. as determined by the Ubbelohde method and an all contentof 50.3% as determined by the acetone-benaene method. The latter methodconsists in extracting the oily wax with a mixture of 65% by volumeacetone and 85% benzene in an amount of 50 ml. of solvent to 1 gram ofwax and separating the wax at --10 1". by filtration. The amount of oildissolved by the acetone-benzene mixture represents the amount of oiloriginally present in the wax. The aforementioned slack wax was acidtreated first with 30 lbs. and then with 45 lbs. of 88% sulfuric acidper barrel of wax at a temperature of 145 to 165 F. The acidtreatedwaxwasthenwashedat175to200F..

with 20% of 2.5 Baum caustic soda, followed by water washing and thenblowing bright with air at 240 1'. A neutral wax was recovered having anoil content of 35.7% and a melting point (Ubbelohde) of 188 1". Thismaterial was then oxidised by blowing it with air at a temperature of450 to 500 F. for about 26 hours, samples being taken at the end of 16,24 and 26 hours of blowing with air.

Test runs in dewaxing an S. A. E. 20 vacuum distillate obtained fromSanta Fe Springs crude oil were made employing 1% of each of theoxidined samples. Dewaxing was carried out in accordanoe with theprocedure outlined in the first example. Yields of dewaxed ofl of 81.2,81.9 and 88.0% by volume having pour points of F., --5 1''. and 21".,respectively, were obtained when employing the 16, 24 and 26 hour airblown samples, respectively. The melting points (Ubbelohde) of theseparated waxes were 125, 127 and 125, respectively, and the filterrates were 8.1, 10.8 and 11.1 slL/lq. ft./hr., respectively.

Another portion of the above oxidized acid treatedB.A.E.50waxwasaddedtoanS.A.E. 50 waxy distillate in amount as to incorporate 0.5%byweightoftheoxidisedwax. The oil was dewaxed according to the propanedewaxing method described above employing, however, a volumetric ratioof two volumes of propane to one oi the oil. A yield of dewaxed oil of64.0% by volume was obtained having a pour point of 1". The meltingpoint (Ubbelohde) of the wax separated was 145 1''. The filter rate was5.8 gal/sq. ft./hr.

From the foregoing example compared with the example of dewaxing the B.'A. 11 50 stock employingtheB.A.E.10oxldiaedwaxasawaxseparation aid, itwill be observed that better yieldsandfilterrateswereobtainedbyusingtheoxidixed8.A.l.50waxontheS.A.E.50waxydistillate.However, the 8. A.E. l0 oxidisedwaxwas more effective as a waxseparation aid in dewaxingtheB.A.E.20waxydistil1ate. Thisindicates thatthe nearer the oxidized wax resembles the type oiwax in the oil to'bedewaxed, the better the yields and filter rates obtained. r

In order to determine the eifect of oil contained in this type of wax.i. e. wax separated from B. A. E. 50 vacuum distillates, two acidtreated waxes and containing, respectively, 50.8% and 11.6% of oil asdetermined by the acetonebenzene method were separately oxidised withpure oxygen. The oxidationv on the two waxes was carried undersubstantially identical conditions. Each wax was oxidized for 22 hoursat a temperature of 450 F. The wax which contained 59.6% or oil had anacid number of 12.0 and a saponification number of 16.3 after oxidation,while the wax 01 low oil content had an acid number of 15.2 and asaponification number oi 85.1.

when S. A. E. vacuum distillates were dewaxed with 1% of the above waxseparation aids and according to the procedure set forth in the firstexample, about 82.3% by volume of dewaxed oil having a pour point of 5F. wax recovered when employing the oxidized wax which had the lower oilcontent. The wax separated from the oil had a melting point (Galician)of 129.5 F. The results obtained employing the oxidized wax oihigher oilcontent were not quite as remarkable, the yield of 011 being 70.1% byvolume of a 5 F. pour point and the melting point of the wax separatedwas only 119 1''.

The above results indicate that it is desirable to deoil the wax to atleast a 40% oil content prior to oxidation with the oxidizing gas.

In another run the slack wax obtained from an S. A. E. waxy distillatewas deoiled by extraction with a mixture of 75% benzene and 25% acetone.The deoiled wax had a melting point (Ubbelohde) of 167 F. The deoiledwax was oxidized in a stream of air and hydrogen peroxide for 8% hoursat a temperature of 380 to 420 1". The finished modifier had an acidnumber of 95. a saponification number of 238 and was quite light incolor. I

The potency of the above described modifier is evidenced by the factthat when the 5. A. E. 20 vacuum distillates heretofore described waspropane dewaxed, using 0.5% of the wax separation aid according to theprocedure herein set forth, a yield of dewaxed oil of 86.9% by volumewas obtained having a pour point of 0 F. The filter rate was 11.5gaL/sq. ft./hr. The wax recovered had a melting point (Ubbelohde) of 128F.

Examples of use of oxidized S. A. E. 20 was A slack wax recovered froman S. A. E. 20 waxy distillate obtained by the vacuum distillation of aSanta Fe Springs crude oil by the propane dewaxing method employingasphalt as a filter aid was deoiled by the acetone-benzene methoddescribed above to an oil content of approximately 8.3%, after which itwas acid treated and wet neutralized. The treated wax had a meltingpoint (A. S. T. 1!. method) of 138.3 1". The material was then oxidizedwith pure oxygen at a temperature 0! 450 F. for 22 hours. The finishedproduct had an acid number of 6.7 and a saponification number of 183.5.

Employing approximately 1% of this wax modifier as a dewaxing aid in thedewaxing of an S. A. E. 20 waxydistillate according tothepropanedewaxingmethod described in the first example with the exception that a higherfilter pressure of 50 to l lbs./sq. in. was employed,

a yield of 83.7% by volume of dewaxed oil having a pour point of F. wasobtained. The filter rate was 3.8 gal/sq. ft./hr. and the melting point(Galician) of the wax separated was 130' F.

In order to determine the effect of the oil content of oxidized S. A..E. 20 wax as a wax modifier, a mixture of 50% of the above describeddeoiled and acid treated wax obtained from the S. A. E. 20 waxydistillate and 50% of dewaxed S. A. E. 20 oil was oxidized with pureoxygen at 450 F. for 22 hours.

When employing 1% of the above oxidized mixture to dewax an S. A. E. 20waxy distillate, it was observed that the yield was rather low, i. e.70.6% by volume. The filter rate, however, was 4.2 gal. per sq. ft./hr.and the pour point of dewaxed oil was F. The melting point (Galician) ofthe wax removed irom the oil was 118 F. These figures would indicatethat while the use of an oxidized S. A. E. 20 wax having a large amountof oil is not as good as a deoiled oxidized wax, it has considerableproperties as a wax modifier. When employingoxidized wax modifiers ofthe S. A. E. 20 type, it is quite desirable to reduce the oil content toapproximately 10-20% prior to oxidation.

In addition to the foregoing oxidized waxes as dewaxing aids, ,we haveobserved that oxidized petrolatum which is a wax recovered from waxcontaining residues and oxidized waxes obtained from S. A. E. 70 waxyoil distillates possess remarkable potency in the dewaxing of petroleumoils. These waxes may or may not be deoiled prior to oxidation to renderthem active as wax modifiers. However, it has been found that the lowerthe oil content of the wax, the more active will be the wax as adewaxing aid after oxidation.

We have also discovered that oxidized waxes of the natural type are alsoeffective in improving the dewaxing characteristics of wax-containingoils. Wax separation aids of this type include oxidized Montan wax,carnauba wax and beeswax.

We have also discovered that oxidized oils are also active in aidingdewaxing of petroleum wax containing fractions. An S. A. E. '70 dewaxedoil produced from a Pennsylvania type crude oil by blending bright stockand neutrals was par-' tially oxidized by being exposed to theatmosphere for three months to a nearly continuous temperature of 340 F.under conditions of considerable agitation. The oxidized oil had an acidnumber of 1.40 and a saponification number of 19. A propane dewaxingrun, employing 1% of the oxidized material with S. A. E. 20 vacuumdistillate was carried out according to the propane dewaxing methoddescribed in the first example. A yield of 79.6% by volume of dewaxedoil having a pour point of -5 1". was obtained. The filter rate was 7.3gaL/sq. ft./hr. The melting point (Galician) of the separated wax was125' F.

While the above experiment was carried out with an oil oxidized for along period of time, it is obvious that the material may be duplicatedor improved by oxidizing the bright stock for a short time under moredrastic conditions of oxidation. Also, similar results may be obtainedby employing the oxidized petroleum fractions after solvent extractionwith a selective solvent such as sulfur dioxide, phenol, nitrobenzol andthe like.

In one case a 650 F. fire point (Cleveland open cup method) steamrefined oil obtained from a Pennsylvania crude oil residuum from whichwax was separated was oxidized for 22 hours at 450 F. with pure oxygen.The acid number of the oxidized oil was 5.3 and the saponificationnumber was 78.0.

When 1% of the above oxidized material was employed as a wax separationaid in propane dewaxing an S. A. E. 20 vacuum distillate in accordanceto the procedure outlined under the first example, a yield of dewaxedoil was obtained of approximately 80.8% by volume having' a pour pointof -10 F. The filter rate was 8.2 gal/sq. ft./hr. The melting point(Galician) oi the wax separated was 128 1".

In another case, a Santa Fe Springsresidual oil which was deasphalted bycommingling the oil with 5 volumes of propane at 70 F. to precipitatethe asphalt was oxidized after removal of propane with pure oxygen at atemperature of 450 F. for 22 hours. When employing 1% of this materialas an aid in propane dewaxing an S. A. E. 20 vacuum distillate,excellent results were obtained with respect to yields of oil of desiredpour point, filter rates and melting point of the separated wax.

We have also obtained improved filter rates by first oxidizing the waxcontaining oil to be dewaxed. that is, instead of adding oxidized wax tothe oil to be dewaxed, the latter is subjected to an oxidation reactionand is subsequently dewaxed by chilling and filter. In one case, a waxcontaining lubricating distillate of S. A. E. 20 grade (from Santa FeSprings crude) was air blown at a temperature of 300 F. forapproximately 22 hours. The rate of air introduction was 6 liters perminute for a 7 liter charge, the air being first passedthrough asulfuric acid trap to remove moisture contained in the air. The oil wasthen mixed at a temperature of 250 F. with liquid propane at avolumetric ratio of 8 volumes of propane to one of the oil. The mixturewas then chilled .to 35 F. by vaporizing propane under graduallyreducing pressure until a pressure of 10 lbs. per square inch existed inthe chilling vessel. The chilled mixture was then filtered under apressure of'less than 25 lbs. per square inch at -30 F. It was foundthat a filter rate of approximately 3.7 gaL/sq. ft./hr. was obtained anda yield of dewaxed oil of 70.7% by volume having a pour point of 5'' F.These figures indicate that by oxidizing the oil to be dewaxed superiorresults may be obtained over dewaxing oils without prior oxidation.

Reference to the hereinbefore mentioned Galician and Ubbelohde methodsfor determining the melting points of wax may be found in the book byHolde entitled Examination of Hydrocarbon Oils and of Saponifiable Fatsand Waxes", 1922, 2nd English Edition.

It will be observed that the foregoing descrip- .tion of our inventionis not to be considered as limiting as many variations thereof may bemade by those skilled in the art within the scope of the followingclaims.

We claim:

1. An oxidized wax produced from a wax-oil mixture containing less thanapproximately 40% oil, said oxidized wax having an acid number of aboutand a saponification number of about 85.

2. An oxidized wax produced from a wax-oil mixture containingapproximately 11.6% oil, said oxidized wax having an acid number ofapproximately 15 and a saponification number of approximately 85.

3. An oxidized wax produced from a wax having a melting point ofapproximately 150 F., said oxidized wax having an acid number ofapproximately 15 and a saponiflcation number of approximately 85.

4. An oxidized wax produced from a wax which has been separated from anS. A. E. 50 waxy lubricating oil distillate, said wax having a meltingpoint of approximately 150 F. and said oxidized wax having an acidnumber of approximately 16 and a saponiflcation number of. approximately82.

amount of oil which comprises deoilingsaid wax to produce a wax of highmelting point, treating said deoiled wax with acid, treating said acidtreated wax with caustic alkali and subsequently oxidizing said treatedwax with an oxygen-containlng gas at a temperature or approximately 450F.

7. A process for the production of oxidized wax from a wax-oil mixturecontaining a substantial amount 01' oil which comprises deoiling saidwax to produce a wax of high melting point, treating said deoiled waxwith acid, treating said acid treated wax with caustic alkali and with-CERTIFICATE Patent No. 2,119,919.

DONALD E.

out separation of all of the alkali from the wax oxidizing said treatedwax with an oxygen-containing gas at a temperature of approximately 450F.

8. A process for the production of OlddlZBd wax from slack wax whichcomprises deoiling said slack wax to produce a wax of high meltingpoint, treating said deoiled wax with sulfuric acid, washing said acidtreated wax, treating said acid treated wax with caustic soda andsubsequently oxidizing said treated wax with air at a temperature ofapproximately 450 F. to 500 F.

9. A process for the production of oxidized wax from a wax-oil mixturecontaining a substantial amount of oil which comprises extracting saidwax-oil mixture with a solvent under conditions such that the oil issoluble but the wax is insoluble, separating the solution of oil andsolvent from the wax, treating the solvent treated wax with acid andalkali and subsequently oxidizing said treated wax with anoxygen-containing-gas at a temperature of approximately 450 F.

10. A process for the production of oxidized wax from a wax-oil mixturecontaining a substantial amount of oil which comprises treating said waxoil mixture with acid and thereby removing a substantial amount oil oilfrom said wax-oil mixture, treating said acid treated oil with an alkalito neutralize the acidity of said acid treated wax-oil mixture andsubsequently oxidizing said treated wax with an oxygen-containing-gas ata temperature of approximately DONALD E. CARR. MANER L. WADE.

OF CORRECTION.

June 7, 19 CARR, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction'as follows: Page 1second colmnn, line 51, for the numeral 51.1" read 5.1;

read Examples;

line 51;, for "Example" page 6, second column, line k2 :for "reducing".read reduced;

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Office.

Sigied. and sealed this th day of August, A. D. 1958.

(Seal) HenryVan Arsdale Acting Goxmnissioner of Patents.

ing a melting point of approximately 150 F., said oxidized wax having anacid number of approximately 15 and a saponiflcation number ofapproximately 85.

4. An oxidized wax produced from a wax which has been separated from anS. A. E. 50 waxy lubricating oil distillate, said wax having a meltingpoint of approximately 150 F. and said oxidized wax having an acidnumber of approximately 16 and a saponiflcation number of. approximately82.

amount of oil which comprises deoilingsaid wax to produce a wax of highmelting point, treating said deoiled wax with acid, treating said acidtreated wax with caustic alkali and subsequently oxidizing said treatedwax with an oxygen-containlng gas at a temperature or approximately 450F.

7. A process for the production of oxidized wax from a wax-oil mixturecontaining a substantial amount 01' oil which comprises deoiling saidwax to produce a wax of high melting point, treating said deoiled waxwith acid, treating said acid treated wax with caustic alkali and with-CERTIFICATE Patent No. 2,119,919.

DONALD E.

out separation of all of the alkali from the wax oxidizing said treatedwax with an oxygen-containing gas at a temperature of approximately 450F.

8. A process for the production of OlddlZBd wax from slack wax whichcomprises deoiling said slack wax to produce a wax of high meltingpoint, treating said deoiled wax with sulfuric acid, washing said acidtreated wax, treating said acid treated wax with caustic soda andsubsequently oxidizing said treated wax with air at a temperature ofapproximately 450 F. to 500 F.

9. A process for the production of oxidized wax from a wax-oil mixturecontaining a substantial amount of oil which comprises extracting saidwax-oil mixture with a solvent under conditions such that the oil issoluble but the wax is insoluble, separating the solution of oil andsolvent from the wax, treating the solvent treated wax with acid andalkali and subsequently oxidizing said treated wax with anoxygen-containing-gas at a temperature of approximately 450 F.

10. A process for the production of oxidized wax from a wax-oil mixturecontaining a substantial amount of oil which comprises treating said waxoil mixture with acid and thereby removing a substantial amount oil oilfrom said wax-oil mixture, treating said acid treated oil with an alkalito neutralize the acidity of said acid treated wax-oil mixture andsubsequently oxidizing said treated wax with an oxygen-containing-gas ata temperature of approximately DONALD E. CARR. MANER L. WADE.

OF CORRECTION.

June 7, 19 CARR, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction'as follows: Page 1second colmnn, line 51, for the numeral 51.1" read 5.1;

read Examples;

line 51;, for "Example" page 6, second column, line k2 :for "reducing".read reduced;

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Office.

Sigied. and sealed this 50th day of August, A. D. 1958.

(Seal) HenryVan Arsdale Acting Goxmnissioner of Patents.

